Microstructure and magnetic domain structure of additively manufactured Fe–Si soft magnetic alloys with 3 and 9 wt.-% Si

Abstract

Electrical steels are numerously used in engineering applications. Nowadays, future challenges related to climate change and e-mobility push the boundaries to higher efficiency also in electrical parts. A promising material group to reduce electrical losses are electrical steels with high silicon contents. However, such steels are difficult to process with conventional methods and, thus, additive manufacturing came into focus in recent years. The present study investigates the processability, crack sensitivity, microstructure evolution and magnetic domain structures of laser powder bed fused Fe–Si alloys with 3 and 9 wt.-% Si. It is shown that specimens, which are built using appropriate process parameters, are dense and free of cracks. Still, Fe–9Si is characterized by a higher crack susceptibility at low temperatures of the build platform. A checkerboard like microstructure with elongated grains alongside build direction evolved. Global magnetic properties from ring core measurements showed lower losses for the Fe–9Si ring. Moreover, it was found that the magnetic domain structures are directly influenced by the crystallographic orientations present in the specimen volumes. The findings elaborated will contribute to advanced possibilities in tailoring the magnetic properties of electrical steels for an increase of the efficiency of envisaged applications.